The long-term aim of this project is an understanding of auditory development in normal children and in specific clinical popultions of children. One major Study Area is the effect of otitis media on auditory development. The specific aim in this area is assessment of the hypothesis that children with a history of otitis media have particular impairment for the processing of speech under particular conditions: when binaural cues are available for masking release, and when the task is designed such that it is difficult to perceptually segregate the speech from masking interference. The second major Study Area assesses the nature of auditory processing deficiencies in children diagnosed with specific language impairment. One specific aim will be to evaluate the hypothesis that such listeners have explicit deficits in coding the temporal aspect of the signal. The competing hypothesis will be assessed that such children have a more general deficit in auditory processing based upon relatively subtle/difficult cues. A related aim will be to control for possible effects of hearing loss history among the children with specific language disorder. The third major Study Area will investigate developmental and basic mechanisms of binaural masking release. Basic experiments on adult listeners will address the question of whether binaural masking release depends upon selective temporal weighting of temporal epochs that are favorable for detection. A related developmental study in this area will investigate the finding that children have reduced MLDs for narrowband noise maskers even though their MLDs are adult- like for relatively wideband maskers. We will examine the hypothesis that children do not take advantage of the narrowband masker valley epochs containing the best signal-to-noise ratios. In all Study Areas, most psychophysical or speech recognition methods will use three-alternative or four- alternative forced-choice testing with sound presentation over earphones. All phases of the project will include age-matched control listeners. Data will be analyzed using analysis of variance and correlation procedures.